|#|Name|Birth and death|Office started|Office ended|
|---|---|---|---|---|
|1|Geir Vídalín|27 October 1761 – 20 September 1823|1801|1823|
|2|Steingrímur Jónsson||1824|1845|
|3|Helgi Thordersen|8 April 1794 – 4 December 1867|1846|1866|
|4|'Pétur Pétursson|3 October 1808 – 15 May 1891|1866|1889|
|5|Hallgrímur Sveinsson|5 April 1841 – 16 December 1909|1889|1908|
|6|Þórhallur Bjarnarson|2 December 1855 – 15 December 1916|1908|1916|
|7|Jón Helgason|1866 – 1942|1917|1939|
|8|Sigurgeir Sigurðsson|3 August 1890 - 13 October 1953|1939|1953|
|9|Ásmundur Guðmundsson|6 October 1888 Reykholt – 29 May 1969 Reykjavík|1954|1989|
|10|Sigurbjörn Einarsson|30 June 1911 Vestur-Skaftafellssýsla – 28 August 2008 Reykjavík|1959|1981|
|11|Pétur Sigurgeirsson (son of Sigurgeir Sigurðsson, 8th Bishop of Iceland)|2 June 1919 – 3 June 2010|1981|1989|
|12|Ólafur Skúlason|29 December 1929 – 9 June 2008|1989|1997|
|13|Karl Sigurbjörnsson (son of Sigurbjörn Einarsson, 10th Bishop of Iceland)|5 February 1947 Reykjavík|1998|2012|
|14|Agnes Sigurðardóttir|19 October 1954 Ísafjörður|24 June 2012|Incumbent|

Question: how many served in the 20th century?
Answer: 9